Photosensitive resin composition, resist laminate, cured product of photosensitive resin composition, and cured product of resist laminate (11)

ABSTRACT

The purpose of the present invention is to provide: a resin composition, a cured product of which has extremely low residual stress and exhibits excellent adhesion to a metal substrate such as a Pt, LT or Ta substrate after a wet heat test in the fields of semiconductors and MEMS/micromachine applications; a laminate of this resin composition; and a cured product of this resin composition or the laminate. The present invention is a photosensitive resin composition which contains an epoxy resin (A), a compound having a phenolic hydroxyl group (B) and a cationic photopolymerization initiator (C), and wherein: the epoxy resin (A) has a weighted average epoxy equivalent weight of 300 g/eq. or more; 20% by mass or more of the epoxy resin (A) is an epoxy resin represented by formula (1) and having an epoxy equivalent weight of 500-4,500 g/eq.; and the compound having a phenolic hydroxyl group (B) contains a phenolic compound having a specific structure.

TECHNICAL FIELD

The present invention relates to a photosensitive resin composition anda cured product thereof. More specifically, the present inventionrelates to a photosensitive resin composition which enables an imagehaving a good sidewall profile and excellent resolution to be formed,whose cured product exhibits a low residual stress and prevents thewarping of a substrate, and which is excellent in the tight adhesion toa substrate after a test for moisture and heat, and a cured product ofthe photosensitive resin composition. The photosensitive resincomposition and the cured product thereof according to the presentinvention having such excellent properties are useful in fabrication ofMEMS (microelectromechanical system) components, μ-TAS (micro totalanalysis system) components, microreactor components, insulating layersof electronic components such as capacitors and inductors, LIGAcomponents, dies and stamps for micro injection molding and heatembossing, screens or stencils for fine printing applications, packagecomponents for MEMS sensors, semiconductor devices and frequencydevices, bio-MEMS and biophotonic devices, inkjet printing headcomponents, and printed wiring boards.

BACKGROUND ART

Among photosensitive resin compositions, photolithographicallyprocessable ones are called photoresists and broadly used forsemiconductors, MEMS and micromachine applications, and the like. Insuch applications, the photolithographic processing is accomplished bycarrying out patterning exposure on a substrate and then selectivelyremoving exposed regions or non-exposed regions by subsequentdevelopment with a developing solution. The photoresists are classifiedinto positive and negative types. Exposed portions are dissolved in adeveloping solution in the positive type, while exposed portions becomeinsoluble in the negative type. In electropackage applications and MEMSapplications of advanced technologies, not only the capacity of forminguniform spin coating films but also a high aspect ratio, a vertical sidewall shape in thick films, and high tight adhesion with substrates andthe like are demanded. Here, the aspect ratio is an important propertywhich is calculated using the ratio of a resist film thickness/a patternline width and indicates the photolithographic performance.

Compositions having a bisphenol A novolac epoxy resin as a majorcomponent disclosed in Patent Literature 1 and Non Patent Literature 1have a very high resolution and the use of the compositions enablesformation of higher-aspect ratio photosensitized images andphotosensitive resin cured products. However, the resin cured productsobtained using the compositions pose such problems that substrates arelargely warped after photolithographic processing using silicon wafersor the like as the substrates thereby damaging fabricated devices anddecreasing the yields due to their remarkably high residual stressvalues. Further, due to the high residual stress, cracks (crazings) aregenerated at the time of development in some cases and exfoliation iseasily generated between the substrates and the resin cured products insome cases.

Patent Literature 2 discloses that a resin composition containing abisphenol epoxy resin, an alicyclic epoxy resin and a cationicphotopolymerization initiator is excellent in the adhesiveness with aNi/Si wafer. Patent Literature 3 discloses that a photosensitive resincomposition containing an epoxy resin having a specific epoxy equivalentand a specific softening point, a phenolic curing agent having aspecific hydroxyl equivalent, and a photoacid generator is excellent inthe adhesiveness with a silicon wafer. Further, Patent Literature 4discloses that a photosensitive resin composition containing a bisphenolepoxy resin, a phenol novolac epoxy resin having a specific structure,and a cationic photopolymerization initiator is excellent in theadhesiveness with a silicon wafer. As a result of studies by the presentinventors, however, it has been found that the resin compositions inthese Patent Literatures were insufficient in the adhesiveness withmetals (substrates) such as Pt and Ta after a test for moisture andheat. Further, the residual stress of the cured products was very highand warping of the substrates was remarkable.

On the other hand, in recent years, in MEMS applications utilizingphotolithographic processing, development has been conducted formanufacture of frequency filter elements such as surface acoustic wavefilters mounted on communication terminals. As a typical one, PatentLiterature 5 discloses a technique in which a frequency filter elementcan be manufactured in a small size and at a low cost by forming aninterdigitated electrode in which a plurality of metal films are layeredon a piezoelectric substrate of lithium tantalate (LT) or the like andusing an organic resin photolithographically processable as aninsulating film on the electrode. However, there have been such defectsthat since the polyimide necessitates a high-temperature curingcondition, it causes damage to devices; and the epoxy resin can be curedat a low temperature, but to due to a high residual stress of the curedproduct, the warping of the substrate, the cracks of the film, and thedegradation in the tight adhesion on the Pt film and the LT substrateafter the moisture and heat treatment tend to occur.

CITATION LIST Patent Literature

-   Patent Literature 1: U.S. Pat. No. 4,882,245-   Patent Literature 2: JP 2002-302536 A-   Patent Literature 3: JP 2008-26667 A-   Patent Literature 4: JP 2010-276694 A-   Patent Literature 5: WO2009/104438

Non Patent Literature

-   Non Patent Literature 1: N. LaBianca and J. D. Gelorme, “High Aspect    Ratio Resist for Thick Film Applications”, Proc. SPIE, vol. 2438, p.    846(1995)

SUMMARY OF INVENTION Technical Problem

The present invention has been achieved in consideration of theabove-mentioned situation and has an object to provide a resincomposition which is an epoxy resin composition to be cured by cationicphotopolymerization and which is very low in the residual stress of itscured product and excellent in the tight adhesion with a metal substrateof Pt, LT, Ta or the like after a test for moisture and heat, and/or alaminate of the resin composition, and a cured product of the resincomposition, in the fields of semiconductors, and MEMS and micromachineapplications.

Solution to Problem

As a result of exhaustive studies, the present inventors have found thatthe above problem can be solved by using a photosensitive resincomposition comprising an epoxy resin having a specific structure, acompound having a specific structure and a phenolic hydroxyl group, anda cationic photopolymerization initiator.

That is, various aspects of the present invention are as follows.

[1]. A photosensitive resin composition comprising: an epoxy resin (A);a compound having phenolic hydroxyl groups (B); and a cationicphotopolymerization initiator (C),

wherein

the epoxy resin (A) has a weighted average epoxy equivalent of 300 g/eq.or higher, and

the epoxy resin (A) comprises 20% by mass or more of an epoxy resinrepresented by the following formula (1):

wherein m is an average value and denotes a real number in the range of3 to 35; and having an epoxy equivalent of 500 to 4,500 g/eq.; and

the compound having phenolic hydroxyl groups (B) comprises at least oneor more phenol compounds selected from the group consisting of phenolcompounds represented by the formulae (2), (4), (5) and (6):

wherein n is an average value and denotes a real number in the range of1 to 10; and each R independently denotes a hydrogen atom or an alkylgroup having 1 to 4 carbon atoms,

wherein q is an average value and denotes a real number in the range of1 to 10,

wherein z is an average value and denotes a real number in the range of1 to 10, and

wherein y is an average value and denotes a real number in the range of1 to 10; and R₈ and R₉ each independently denote a hydrogen atom or analkyl group having 1 to 4 carbon atoms.

[2]. The photosensitive resin composition according to the above [1],wherein the epoxy resin (A) comprises an epoxy resin represented by thefollowing formula (3):

wherein a is an average value and denotes a real number in the range of2 to 30; and each X independently denotes a hydrogen atom or a glycidylgroup and at least one of the plurality of X is a glycidyl group.

[3]. The photosensitive resin composition according to the above [1] or[2], comprising 0.1 to 0.9 equivalents of the compound having phenolichydroxyl groups (B) with respect to 1 equivalent of the epoxy resin (A).

[4]. The photosensitive resin composition according to any one of theabove [1] to [3], wherein the cationic photopolymerization initiator (C)is a cationic photopolymerization initiator of an onium complex salt.

[5]. The photosensitive resin composition according to any one of theabove [1] to [4], comprising an epoxy group-containing silane compound(D).

[6]. The photosensitive resin composition according to any one of theabove [1] to [5], comprising a solvent (E).

[7]. A cured product of the photosensitive resin composition accordingto any one of the above [1] to [6].

[8]. A resist laminate obtained by interposing the photosensitive resincomposition according to any one of the above [1] to [6] betweensubstrates.

[9]. A cured product of a dry film resist obtained from the resistlaminate according to the above [8].

Advantageous Effects of Invention

The photosensitive resin composition according to the present inventionallows formation of a pattern having a fine and vertical side wall shapeby photolithography. Its cured product has properties high in theresolution, high in the sensitivity, and excellent in the tight adhesionwith a metal substrate of Pt, LT, Ta or the like after a test formoisture and heat. Hence, by using the photosensitive resin compositionaccording to the present invention, a permanent resist and a curedproduct can be provided with properties required in the fields ofsemiconductors and MEMS and micromachine applications, particularlypackage components for MEMS devices, semiconductor devices and frequencyfilter devices, components for forming microreactors, and inkjetprinting head components.

DESCRIPTION OF EMBODIMENTS

Hereinafter, the present invention will be described.

The photosensitive resin composition according to the present inventioncomprises an epoxy resin (A) having a weighted average epoxy equivalentof 300 g/eq. or higher. The term weighted average epoxy equivalentreferred to herein means a weighted average epoxy equivalent of allepoxy resins contained in the epoxy resin (A); for example, the weightedaverage epoxy equivalent in the case of containing 2 mol of an epoxyresin having an epoxy equivalent of 100 g/eq. and 1 mol of an epoxyresin having an epoxy equivalent of 400 g/eq. is estimated to be (100×2mol+400×1 mol)/(2 mol+1 mol)=200 g/eq. Here, the epoxy equivalent in thepresent invention means a measurement value acquired according to JISK7236. The weighted average epoxy equivalent is more preferably 400g/eq. or higher.

The epoxy resin (A) contained in the photosensitive resin compositionaccording to the present invention comprises a bifunctional epoxy resincommonly referred to as a bisphenol F epoxy resin (compound) andrepresented by the above formula (1).

In the formula (1), m is an average value and denotes a real number inthe range of 3 to 35. The “average value” referred to herein means anaverage repeating number. For example, the average value m of an epoxyresin containing 1 mol of the compound with the structure having m of 2in the formula (1), 2 mol of the compound with the structure having m of3 therein, 3 mol of the compound with the structure having m of 4therein, and 1 mol of the compound with the structure having m of 5therein is estimated to be (2×1 mol+3×2 mol+4×3 mol+5×1 mol)/(1 mol+2mol+3 mol+1 mol)≈3.57. Similarly, the average value m of an epoxy resincontaining 2 mol of the compound with the structure having m of 0, 3 molof the compound with the structure having m of 5, 3 mol of the compoundwith the structure having m of 6, 3 mol of the compound with thestructure having m of 7, and 1 mol of the compound with the structurehaving m of 32 is estimated to be (0×2 mol+5×3 mol+6×3 mol+7×3 mol+32×1mol)/(2 mol+3 mol+3 mol+3 mol+1 mol)≈7.17. That is, in the epoxy resinrepresented by the formula (1) contained in the photosensitive resincomposition according to the present invention, a compound in which m inthe formula (1) is 0 or more and less than 3 and/or an epoxy resin (oran epoxy compound) in which m in the formula (1) is more than 35 may beused concurrently, as long as the average value m is in the range of 3to 35.

The epoxy equivalent of the epoxy resin represented by the formula (1)is usually 500 to 4,500 g/eq. The epoxy equivalent is more preferably700 to 3,000 g/eq from the viewpoint of the sensitivity and thedevelopability of the photosensitive resin composition and the strengthand the durability of the cured product. The average value m of theepoxy resins represented by the formula (1) having such preferable epoxyequivalents is 4 to 22.

Examples of commercially available products of bisphenol F epoxy resinshaving an average value m of 3 to 35 include jER4004P (m in the formula(1) is about 5.3 to 6.4, epoxy equivalent: 840 to 975 g/eq.), jER4005P(m in the formula (1) is about 6.2 to 8.2, epoxy equivalent: 950 to1,200 g/eq.), jER4007P (m in the formula (1) is about 14.4 to 18.3,epoxy equivalent: 2,000 to 2,500 g/eq.) and jER4010P (m in the formula(1) is about 28.5 to 34.7, epoxy equivalent: 3,800 to 4,600 g/eq.),which are commercially available from Mitsubishi Chemical Corp.

In the photosensitive resin composition according to the presentinvention, one or more epoxy resins (compounds) other than the epoxyresin represented by the formula (1), reactive epoxy monomers, and thelike may be used concurrently as long as the weighted average epoxyequivalent of the epoxy resin (A) is in the range of 300 g/eq. orhigher.

Examples of commercially available products of bisphenol F epoxy resinshaving an average value m in the formula (1) of less than 3 that can beused concurrently include YDF-8170C (m in the formula (1) is about 0 toabout 0.1, epoxy equivalent: 155 to 165 g/eq.), commercially availablefrom Nippon Steel & Sumikin Chemical Co., Ltd., jER806 (m in the formula(1) is 0 to about 0.1, epoxy equivalent: 160 to 170 g/eq.) and jER807 (min the formula (1) is 0 to about 0.2, epoxy equivalent: 160 to 175g/eq.), commercially available from Mitsubishi Chemical Corp., andEPICLON EXA830CRP (m in the formula (1) is 0 to about 0.1, epoxyequivalent: 155 to 163 g/eq.) and EPICLON EXA835LV (m in the formula (1)is 0 to about 0.1, epoxy equivalent: 160 to 170 g/eq.), commerciallyavailable from DIC Corp.

It is preferable that a bisphenol F epoxy resin having three or moreepoxy groups in one molecule thereof represented by the above formula(3) is used concurrently in the photosensitive resin compositionaccording to the present invention.

In the formula (3), a is an average value and denotes a real number inthe range of 2 to 30. The “average value” referred to herein means anaverage repeating number.

The epoxy resin represented by the formula (3) can be obtained byglycidylating alcoholic hydroxyl groups of polycondensates of bisphenolF with epichlorohydrin by further using epichlorohydrin. The proportionof the alcoholic hydroxyl groups to be further glycidylated is notespecially limited, but in consideration of the balance of variousphysical properties, the epoxy resin is preferably an epoxy resin inwhich about 50 to 80% of the alcoholic hydroxyl groups of thepolycondensates of bisphenol F with epichlorohydrin is glycidylated.

Specific examples of commercially available products of the epoxy resinrepresented by the formula (3) include NER-7604 and NER-7403 (both aretrade names, commercially available from Nippon Kayaku Co., Ltd.). Theepoxy equivalent of the epoxy resin represented by the formula (3) ispreferably 250 to 400 g/eq., and the softening point thereof ispreferably 60 to 85° C.

Examples of the other epoxy resins (compounds) which may be usedconcurrently include Epikote 157 (trade name, bisphenol A novolac epoxyresin, commercially available from Mitsubishi Chemical Corp., epoxyequivalent: 180 to 250 g/eq., softening point: 80 to 90° C.), EPON SU-8(trade name, bisphenol A novolac epoxy resin, commercially availablefrom Momentive Performance Materials Inc., epoxy equivalent: 195 to 230g/eq.), NC-3000 (trade name, biphenyl-phenol novolac epoxy resin,commercially available from Nippon Kayaku Co., Ltd., epoxy equivalent:270 to 300 g/eq.), NER-1302 (trade name, bisphenol A epoxy resin inwhich a part of alcoholic hydroxyl groups is epoxidized, commerciallyavailable from Nippon Kayaku Co., Ltd., epoxy equivalent: 200 to 500g/eq.), EOCN-1020 (trade name, commercially available from Nippon KayakuCo., Ltd., epoxy equivalent: 190 to 210 g/eq.) and NC-6300H (trade name,commercially available from Nippon Kayaku Co., Ltd., epoxy equivalent:230 to 235 g/eq.). According to one embodiment of the present invention,the epoxy resin contains no bisphenol A novolac epoxy resin.

Specific examples of the reactive epoxy monomers which may be usedconcurrently include diethylene glycol diglycidyl ether, hexanedioldiglycidyl ether, dimethylolpropane diglycidyl ether, polypropyleneglycol diglycidyl ether (commercially available from Adeka Corp.,ED506), trimethylolpropane triglycidyl ether (commercially availablefrom Adeka Corp., ED505), trimethylolpropane triglycidyl ether(low-chlorine type, commercially available from Nagase ChemteX Corp.,EX321L), and pentaerythritol tetraglycidyl ether.

In the case of concurrently using epoxy resins other than the epoxyresin represented by the formula (1), the proportion of the epoxy resinrepresented by the formula (1) accounted for in the whole epoxy resin(A) is usually 20% by mass or higher, and preferably 35% by mass orhigher.

The compound having phenolic hydroxyl groups (B) contained in thephotosensitive resin composition according to the present inventioncomprises one or more phenol compounds selected from the groupconsisting of phenol compounds represented by the above formulae (2),(4), (5) and (6). Here, the “average value” meant by n, q, z or y in theformula (2), (4), (5) or (6) means an average repeating number.

Specific examples of the phenol compounds represented by the formula (2)include phenol novolacs and cresol novolacs; and phenol novolacs, sincetheir photosensitive resin composition is excellent in coatability, arepreferably used. As the phenol compound represented by the formula (2),those having a softening temperature of 50° C. or higher and 150° C. orlower are preferable, those having a softening temperature of 50° C. orhigher and 100° C. or lower are more preferable, and those having asoftening temperature of 70° C. or higher and 100° C. or lower are stillmore preferable. Specific examples of the phenol novolacs having asoftening temperature of 50° C. or higher and 150° C. or lower includePN-152 (trade name, commercially available from Meiwa Plastic IndustriesLtd., softening point: 50° C., hydroxyl equivalent: 105 g/eq.), H-1(trade name, commercially available from Meiwa Plastic Industries Ltd.,softening point: 80° C., hydroxyl equivalent: 104 g/eq.), TD-2131 (tradename, commercially available from DIC Corp., softening point: 80° C.,hydroxyl equivalent: 105 g/eq.), and KA-1160 (trade name, commerciallyavailable from DIC Corp., softening point: 81° C., hydroxyl equivalent:117 g/eq.). The hydroxyl equivalent of the phenol novolacs is, from theviewpoint of the compatibility with the epoxy resin (A) and the lowmoisture permeability of the cured product, preferably in the range of80 to 200 g/eq., more preferably in the range of 80 to 130 g/eq., andstill more preferably in the range of 100 to 120 g/eq.

For the compound having phenolic hydroxyl groups (B), a plurality ofphenol compounds represented by the formula (2) may be usedconcurrently.

The phenol compound represented by the formula (4) includes bisphenol Anovolacs. Specific examples thereof include VH-4150 (trade name,commercially available from DIC Corp., softening point: 85° C., hydroxylequivalent: 118 g/eq.), VH-4170 (trade name, commercially available fromDIC Corp., softening point: 103° C., hydroxyl equivalent: 118 g/eq.),and MEP-6309E (trade name, commercially available from Meiwa PlasticIndustries Ltd., softening point: 81° C., hydroxyl equivalent: 116g/eq.).

For the compound having phenolic hydroxyl groups (B), a plurality ofphenol compounds represented by the formula (4) may be usedconcurrently.

The phenol compound represented by the formula (5) includes biphenylphenol novolacs. Specific examples thereof include KAYAHARD GPH-65(trade name, commercially available from Nippon Kayaku Co., Ltd.,softening point: 65° C., hydroxyl equivalent: 200 g/eq.).

For the compound having phenolic hydroxyl groups (B) a plurality ofphenol compounds represented by the formula (5) may be usedconcurrently.

The phenol compound represented by the formula (6) includes phenolaralkyl resins; and specific examples thereof include Milex XLC-3L(trade name, commercially available from Mitsui Chemicals Inc.,softening point: 77° C., hydroxyl equivalent: 176 g/eq.).

For the compound having phenolic hydroxyl groups (B), a plurality ofphenol compounds represented by the formula (6) may be usedconcurrently.

According to one preferable embodiment of the present invention, thecompound having phenolic hydroxyl groups (B) comprises one or morephenolic compounds selected from the group consisting of phenolcompounds represented by the formulae (2), (5) and (6).

With respect to the content of the compound having phenolic hydroxylgroups (B) in the photosensitive resin composition according to thepresent invention, the hydroxyl equivalent of the compound havingphenolic hydroxide groups (B) is, with respect to 1 equivalent of anepoxy group of the epoxy resin (A), usually 0.1 to 0.9 equivalents, andpreferably 0.2 to 0.5 equivalents. When the content of the compoundhaving phenolic hydroxyl groups (B) is 0.9 equivalents or lower, thedevelopability good in the photosensitized image pattern can beprovided; and when the content is 0.1 equivalents or higher, theadhesiveness of the cured product with a substrate and the moistureresistance thereof can be maintained.

Here, in the case of concurrently using a plurality of the compoundshaving phenolic hydroxyl groups represented by the formulae (2), (4),(5) and (6), the proportion of use of each of the compounds havingphenolic hydroxyl groups is not especially limited as long as the totalamount of the plurality of the compounds contained in the phenolcompound having phenolic hydroxyl groups (B) with respect to the mass ofthe epoxy resin (A) is in the above range.

In the photosensitive resin composition according to the presentinvention, a compound(s) having phenolic hydroxyl groups other than thephenol compounds represented by the formulae (2), (4), (5) or (6) may beused concurrently in the range not impairing the advantages of thepresent invention.

Examples of the compound having phenolic hydroxyl groups which may beused concurrently include the phenol compounds described as a rawmaterial of the epoxy resin in the paragraph of the epoxy resins whichmay be used concurrently, but are not limited thereto.

The cationic photopolymerization initiator (C) contained in thephotosensitive resin composition according to the present invention is acompound which generates a cation upon irradiation with radiation suchas ultraviolet rays, far ultraviolet rays, laser light such as KrF andArF, X-rays and electron beams, the cation being capable of acting as apolymerization initiator of the epoxy resin (A). The cationicphotopolymerization initiator (C) includes onium complex salts. Theonium complex salts typically include aromatic iodonium complex saltsand aromatic sulfonium complex salts. Among them, specific examples ofthe aromatic iodonium complex salts include diphenyliodoniumtetrakis(pentafluorophenyl)borate, diphenyliodonium hexafluorophosphate,diphenyliodonium hexafluoroantimonate, di(4-nonylphenyl)iodoniumhexafluorophosphate, tolylcumyliodoniumtetrakis(pentafluorophenyl)borate (commercially available from RhodiaChemie, trade name: Rhodorsil PI2074), and di(4-tertiarybutyl)iodoniumtris(trifluoromethanesulfonyl)methanide (commercially available fromBASF, trade name: CGI BBI-C1).

Further, specific examples of the aromatic sulfonium complex saltsinclude 4-thiophenyldiphenylsulfonium hexafluoroantimonate (commerciallyavailable from San-Apro Ltd., trade name: CPI-101A),thiophenyldiphenylsulfonium tris(pentafluoroethyl)trifluorophosphate(commercially available from San-Apro Ltd., trade name: CPI-210S),4-{4-(2-chlorobenzoyl)phenylthio}phenylbis(4-fluorophenyl)sulfoniumhexafluoroantimonate (commercially available from Adeka Corp., tradename: SP-172), a mixture of aromatic sulfonium hexafluoroantimonatescontaining 4-thiophenyldiphenylsulfonium hexafluoroantimonate(commercially available from Aceto Corp., USA, trade name: CPI-6976),triphenylsulfonium tris(trifluoromethanesulfonyl)methide (commerciallyavailable from BASF, trade name: CGI TPS-C1),tris[4-(4-acetylphenyl)sulfonylphenyl]sulfoniumtris(trifluoromethylsulfonyl)methide (commercially available from BASF,trade name: GSID 26-1), andtris[4-(4-acetylphenyl)sulfonylphenyl]sulfoniumtetrakis(2,3,4,5,6-pentafluorophenyl)borate (commercially available fromBASF, trade name: Irgacure PAG290). Hexafluoroantimonate salts, althoughbeing inexpensive, since being liable to generate hydrogen fluoride bytheir decomposition, are suitable for applications not directlycontacting with any metal. Methide salts and borate salts, sincegenerating no hydrogen fluoride, can be suitably used in anyapplications including applications contacting with a metal. These canbe used singly or in a combination of two or more thereof.

The content of the cationic photopolymerization initiator (C) in thephotosensitive resin composition according to the present invention is,with respect to the solid content (i.e. the total amount of allcomponents excluding solvents; hereinafter, the same meaning is applied)of the photosensitive resin composition according to the presentinvention, usually 0.3 to 15% by mass, and preferably 0.5 to 10% bymass.

The photosensitive resin composition according to the present inventionmay further comprise the epoxy group-containing silane compound (D).When the composition according to the present invention comprises theepoxy group-containing silane compound (D), there can be improved theadhesiveness with a substrate and the interlayer adhesiveness in thecase where a multilayer structure is formed from the compositionaccording to the present invention. Specific examples of the epoxygroup-containing silane compound (D) include epoxy group-containingalkoxysilane compounds such as 3-glycidoxypropyltrimethoxysilane,3-glycidoxypropylmethyldimethoxysilane,3-glycidoxypropyltriethoxysilane, and2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. These can be used singlyor in a combination of two or more thereof.

The content of the epoxy group-containing silane compound (D) in thephotosensitive resin composition according to the present invention is,with respect to the solid content of the photosensitive resincomposition, usually 15% by mass or lower, and preferably 1 to 10% bymass.

The photosensitive resin composition according to the present inventioncan use the solvent (E) in order to reduce the viscosity of thephotosensitive resin composition and improve the coatability. Thesolvent usable is not especially limited as long as being an organicsolvent usually used for inks, coating materials and the like, beingcapable of dissolving each constituent of the photosensitive resincomposition, and not causing a chemical reaction with the constituents.Specific examples of the solvent (E) include ketones such as acetone,ethyl methyl ketone, methyl isobutyl ketone and cyclopentanone, aromatichydrocarbons such as toluene, xylene and methoxybenzene, glycol etherssuch as dipropylene glycol dimethyl ether, dipropylene glycol diethylether and propylene glycol monomethyl ether, esters such as ethyllactate, ethyl acetate, butyl acetate, methyl 3-methoxypropionate,carbitol acetate, propylene glycol monomethyl ether acetate andγ-butyrolactone, alcohols such as methanol and ethanol, aliphatichydrocarbons such as octane and decane, and petroleum solvents such aspetroleum ethers, petroleum naphthas, hydrogenated petroleum naphthasand solvent naphthas. These solvents can be used singly or as a mixtureof two or more thereof.

The content of the solvent (E) in the photosensitive resin compositionaccording to the present invention is, in the photosensitive resincomposition containing the solvent, usually 95% by mass or lower, andpreferably 10 to 90% by mass.

The photosensitive resin composition according to the present inventionmay further comprise a sensitizer in order to absorb ultraviolet rays,and give the absorbed light energy to the cationic photopolymerizationinitiator, particularly, to the aromatic iodonium complex salt. As thesensitizer, there are preferable, for example, thioxanthones andanthracene compounds having alkoxy groups at the 9-position and the10-position thereof (9,10-dialkoxyanthracene derivatives). Examples ofthe alkoxy group include C₁ to C₄ alkoxy groups such as a methoxy group,an ethoxy group, a propoxy group and a butoxy group. The9,10-dialkoxyanthracene derivatives may further have substituents.Examples of the substituents include halogen atoms such as a fluorineatom, a chlorine atom, a bromine atom and an iodine atom, C₁ to C₄ alkylgroups, alkyl sulfonate groups and alkyl carboxylate groups. Examples ofthe alkyl group in the alkyl sulfonate groups or alkyl carboxylategroups include C₁ to C₄ alkyl groups. The substitution position of thesesubstituents is preferably the 2-position.

Specific examples of the thioxanthones include 2,4-dimethylthioxanthone,2,4-diethylthioxanthone, 2-chlorothioxanthone, and2,4-diisopropylthioxanthone. Among them, preferable are2,4-diethylthioxanthone (commercially available from Nippon Kayaku Co.,Ltd., trade name: Kayacure DETX-S), and 2-isopropylthioxanthone.

Examples of the 9,10-dialkoxyanthracene derivatives include9,10-dimethoxyanthracene, 9,10-diethoxyanthracene,9,10-dipropoxyanthracene, 9,10-dibutoxyanthracene,9,10-dimethoxy-2-ethylanthracene, 9,10-diethoxy-2-ethylanthracene,9,10-dipropoxy-2-ethylanthracene, 9,10-dimethoxy-2-chloroanthracene,9,10-dimethoxyanthracene-2-sulfonate methyl ester,9,10-diethoxyanthracene-2-sulfonate methyl ester, and9,10-dimethoxyanthracene-2-carboxylate methyl ester.

These sensitizers can be used singly or as a mixture of two or morethereof, but use of 2,4-diethylthioxanthone and9,10-dimethoxy-2-ethylanthracene is most preferable. Since thesensitizer component exhibits the effect in a small amount thereof, thecontent of the sensitizer in the photosensitive resin compositionaccording to the present invention is, with respect to the content ofthe cationic photopolymerization initiator (C), usually 30% by mass orlower, and preferably 20% by mass or lower.

To the photosensitive resin composition according to the presentinvention, an ion catcher may be added, as required, in the case wherethe adverse effects of ions originated from the cationicphotopolymerization initiator (C) should be reduced. Specific examplesof the ion catcher include alkoxyaluminums such as trismethoxyaluminum,trisethoxyaluminum, trisisopropoxyaluminum, isopropoxydiethoxyaluminumand trisbutoxyaluminum, phenoxyaluminums such as trisphenoxyaluminum andtrisparamethylphenoxyaluminum, and organoaluminum compounds such astrisacetoxyaluminum, trisstearatoaluminum, trisbutylatoaluminum,trispropionatoaluminum, trisacetylacetonatoaluminum,tristrifluoroacetylacetonatoaluminum, trisethylacetoacetatoaluminum,diacetylacetonatodipivaloylmethanatoaluminum anddiisopropoxy(ethylacetoacetato)aluminum. These components can be usedsingly or in a combination of two or more thereof. The content of theion catcher is, with respect to the solid content of the photosensitiveresin composition according to the present invention, usually 10% bymass or lower.

In the photosensitive resin composition according to the presentinvention, a various additive(s) such as thermoplastic resins,colorants, thickeners, defoaming agents and leveling agents can be used,as required. Examples of the thermoplastic resins include polyethersulfone, polystyrene and polycarbonate. Examples of the colorantsinclude Phthalocyanine Blue, Phthalocyanine Green, Iodine Green, CrystalViolet, titanium oxide, carbon black, Naphthalene Black, AnthraquinoneRed, Quinacridone Red, and Diketopyrrolopyrrole Red. Examples of thethickeners include Olben, Bentone and montmorillonite. Examples of thedefoaming agents include silicone defoaming agents, fluoroalkyldefoaming agents, polymeric defoaming agents and other types. In thecase of using these additives and the like, their contents are each,with respect to the solid content of the photosensitive resincomposition according to the present invention, 10% by mass or lower asa sort of measure, but can suitably be increased or decreased accordingto the use purpose and the coating quality.

In the photosensitive resin composition according to the presentinvention, optional inorganic fillers such as barium sulfate, bariumtitanate, silicon oxide, amorphous silica, talc, clay, magnesiumcarbonate, calcium carbonate, aluminum oxide, aluminum hydroxide,montmorillonite and mica powder, and optional organic fillers such aspolymethyl methacrylate, rubber, fluoropolymer and polyurethane powdercan be used. The content of these inorganic and/or organic fillers is,with respect to the solid content of the photosensitive resincomposition according to the present invention, 60% by mass or lower asa sort of measure, but can suitably be increased or decreased accordingto the use purpose and the function required for the cured film.

The photosensitive resin composition according to the present inventioncan be prepared by mixing and stirring, by a usual method, essentialcomponents of the epoxy resin (A), the compound having phenolic hydroxylgroups (B) and the cationic photopolymerization initiator (C), and asrequired, the epoxy group-containing silane coupling agent (D), thesolvent (E) and the optional components such as the sensitizer, the ioncatcher, the thermoplastic resin, the colorant, the thickener, thedefoaming agent, the leveling agent and the inorganic fillers. In themixing and stirring, there may be used, as required, a dispersingmachine such as a dissolver, a homogenizer or a three-roll mill. Furtherafter the mixing, filtration may be carried out by using a mesh, amembrane filter or the like.

The photosensitive resin composition according to the present inventioncan be used, for being coated on a substrate, preferably in a liquidform containing a solvent added therein. The photosensitive resincomposition according to the present invention can be applied in adesired film thickness by controlling the rotating speed in a spin coatmethod comprising a step of dropping the photosensitive resincomposition according to the present invention diluted to a desiredviscosity with the solvent on the substrate, accelerating the substrateup to a certain rotating speed, and thereafter holding the rotatingspeed. Alternatively, the photosensitive resin composition can also beapplied onto a substrate by another coating method such as rollercoating, doctor knife coating, slot coating, dip coating, gravurecoating or spray coating. After the coating, dry baking is carried outto evaporate the solvent. The dry baking conditions can be selected soas to form a semi-cured dry coating film of a photoresist. Typicalconditions thereof involves bringing the substrate into contact or nearcontact with a hot plate having a smooth surface, and heating thesubstrate at 65° C. for 1 to 15 minutes, and then at 90 to 125° C. for 5to 120 minutes depending on the thickness of the coating film, thevolatility of the solvent, and the heat conductivity and the thicknessof the substrate. Alternatively, the dry baking can be carried out in aconvection-type oven. Then, a photosensitized image can be formed in thedried photosensitive resin composition layer by exposure using nearultraviolet rays or 300 to 500-nm bright lines from a medium orextra-high pressure mercury lamp through a photomask having a desiredmask pattern drawn thereon, irradiation using energy rays of X-rayradiation from a synchrotron radiation source, or irradiation withelectron beam radiation through direct or patterned exposure. In themask exposure, contact, proximity or projection printing can be used.Following the exposure, in order to promote the polymerization reactionby an acid catalytic action in the exposed region on the photosensitiveresin composition layer, post-exposure baking can be carried out.Typical conditions thereof involve baking on a hot plate at 65° C. for 1to 5 minutes, and then at 95° C. for 1 to 60 minutes depending on thethickness of the coating film, and the heat conductivity and thethickness of the substrate.

Then, in order to dissolve and remove unexposed portions, the coatingfilm is immersed typically in an organic solvent developing solution for2 to 30 minutes depending on the thickness of the coating film and thesolvent titer of the developing solution solvent. Further, the developedimage is rinsed by applying a rinsing solvent thereby removing thedeveloping solution adhered on the cured film. The adhered developingsolution needs to be removed because of containing photoresistcomponents dissolved therein and making scums on the photosensitizedimages when being dried thereby easily causing formation of stains. Inthe case of the dipping method, by preparing a clean developing solutiontank and carrying out development on multistage, the adhesion of thescums is enabled to be prevented.

Alternatively, the developing solution solvent may be applied byspraying with the use of either an explosionproof spray nozzle foratomization or an explosionproof fine shower head spray nozzle. Further,other developing methods include a method of applying a developingsolution by using a paddle method.

Examples of the developing solution include propylene glycol monomethylether acetate, γ-butyrolactone, acetone, cyclopentanone, diacetonealcohol, tetrahydrofurfuryl alcohol, N-methylpyrrolidone, anisole, andethyl lactate, but is not limited thereto. Use of propylene glycolmonomethyl ether acetate, which is good in the solubility of unexposedportions and is relatively inexpensive, is preferable.

Examples of the rinsing solution include the above developing solutionsolvents, and methanol, ethanol, isopropanol and n-butyl acetate. Amongthem, especially preferable are acetone, ethanol and isopropanol, whichcan be fast cleaned and speedily dried. Finally, the coating film can besubjected to a thermal treatment at 130 to 200° C. so as to cure thefilm with heat according to the heat resistance of the substrate therebyobtaining a permanent protecting film satisfying various properties.

Examples of the materials for the substrate usable for thephotosensitive resin composition according to the present inventioninclude, but not limited to, substrates having patterning regions oforganic films, metals, semiconductors and insulating materials, such assilicon, silicon dioxide, silicon nitride, alumina, glass,glass-ceramics, gallium arsenide, indium phosphide, copper, aluminum,nickel, iron, steel, copper-silicon alloys, indium-tin oxide-coatedglass, polyimide and polyester. Since the photosensitive resincomposition according to the present invention is excellent in theadhesiveness with a substrate of Pt, LT, Au, Ta or the like, use ofthese metal substrates or substrates having such a metal layer on thesurface is preferable.

The photosensitive resin composition according to the present inventioncan also be used as a resist laminate by being interposed betweensubstrates. A resist laminate can be obtained, for example, by applyingthe photosensitive resin composition diluted with a solvent on a basefilm (i.e. a substrate) by using a roll coater, a die coater, a knifecoater, a bar coater, a gravure coater or the like, and thereafterremoving the solvent in a drying oven set at 45 to 100° C., and asrequired, further laminating a cover film (i.e. a substrate) or thelike. At this time, the thickness of the resist on the base film can beregulated at 2 to 100 μm. As the base film or the cover film being asubstrate, for example, a film such as polyester, polypropylene,polyethylene, TAC and polyimide can be used. As required, these filmsmay be ones having been subjected to a release treatment with a siliconerelease treating agent, a non-silicone release treating agent or thelike. When using such a resist laminate, for example, the followingsteps may be performed: the cover film is peeled off, and thephotosensitive resin composition is transferred to a substrate at atemperature of 40 to 100° C. at a pressure of 0.05 to 2 MPa by a handroller, a laminator or the like, and as in the above liquidphotosensitive resin composition, subjected to exposure, post-exposurebaking, development, and heat treatment.

If the photosensitive resin composition is used as a dry film resist byusing the resist laminate according to the present invention, the stepsof applying the composition to a support or substrate and drying it canbe omitted, thus allowing the photosensitive resin composition accordingto the present invention to form fine patterns more simply.

In the case where the photosensitive resin composition according to thepresent invention is used as package components of MEMS devices,semiconductor devices and frequency filter devices, components forforming microreactors, and inkjet printing head components, thephotosensitive resin composition is applied onto a substrate and driedthereby forming a photosensitive resin coating film as a first layer.The first layer is then subjected to exposure and post-exposure baking.Further, the photosensitive resin composition according to the presentinvention is applied thereto and dried thereby forming a photosensitiveresin coating film as a second layer; and thereafter, the second layeris subjected to exposure and post-exposure baking. This step may berepeated a plurality of times; and finally, the resultant may besubjected to development and hard baking treatments altogether, by whicha complex multilayer structure pattern can be formed. Alternatively, amultilayer structure pattern may be formed by developing a first layerand hard baking, which may be followed by applying and drying a secondlayer and subjecting to an alignment exposure through a photomask, andrepeating development and hard baking. Alternatively, the formation ofeach photosensitive resin layer may be by lamination of a dry filmresist.

Here, the term “package” refers to an encapsulating method or anencapsulated product to be used for blocking infiltration of outsidegases and liquids in order to keep the stability of substrates,interconnects, elements and the like. Examples of the package referredto herein include packages having a driving part like MEMS, hollowpackages for packaging a vibrator such as SAW devices, surfaceprotection in order to prevent the degradation of semiconductorsubstrates, printed wiring boards, interconnects, components for formingmicroreactors, resin encapsulations in order to seal these componentswith a top plate, and the like. The term “wafer-level package”represents a manufacturing method in which the installation of aprotecting film and terminals, interconnect processing and the packagingare carried out in the state of a wafer, and the wafer is then slicedinto individual chips, or a manufacturing method in which fine micro- tonano-flow paths and an orifice plate for an inkjet nozzle arethree-dimensionally processed altogether in a wafer.

The use of the photosensitive resin composition according to the presentinvention allows formation of patterns having a fine and vertical sidewall shape by photolithography. Its cured product has propertiesexcellent in low stress, small warping and resistance to moisture andheat. There can be provided a permanent resist and a cured productsatisfying properties required for semiconductors and MEMS andmicromachine application fields, particularly package components of MEMSdevices, semiconductor devices and frequency filter devices, componentsfor forming microreactors, and inkjet printing head components; and thepermanent resist and the cured product are greatly useful in thesefields.

EXAMPLES

Hereinafter, the present invention will be described in more detail byway of Examples, but these Examples are only illustrations toconveniently explain the present invention, and do not limit the scopeof the present invention by any means.

Examples 1 to 10 and Comparative Examples 1 to 4

(Preparation of Photosensitive Resin Composition Solutions (LiquidResists))

A mixture of epoxy resins (A), a compound having phenolic hydroxylgroups (B), a cationic photopolymerization initiator (C) and an epoxygroup-containing silane compound (D) in the blend amounts (unit: part bymass, indicating masses of solid content alone excluding solvent)described in Table 1 was diluted with cyclopentanone so that theconcentration became 65% by mass, and stirred, mixed and dissolved in aflask with a stirrer at 80° C. for 3 hours, allowed to cool, andthereafter subjected to filtration using a membrane filter of 1.0 μm inpore diameter, by which each of photosensitive resin compositionsolutions (liquid resists) according to the present invention and forcomparison was obtained.

(Evaluations of the Sensitivity and the Resolution of the PhotosensitiveResin Compositions)

Each of the liquid resists obtained in Examples 1 to 10 and ComparativeExamples 1 to 4 was applied onto a silicon wafer by a spin coater, andthereafter pre-baked by a hot plate at 95° C. for 10 minutes therebyobtaining a photosensitive resin composition layer of 20 μm in dry filmthickness after application. Thereafter, the photosensitive resincomposition layer was cleared of edge beads and dried, and thenirradiated with an exposure dose of 700 mJ/cm² (soft contact, i line)through a gray scale photomask for evaluation of resolution by using ani line exposure apparatus (mask aligner, commercially available fromUshio Inc.). Then, the irradiated photosensitive resin composition layerwas post-exposure baked (hereinafter, referred to as “PEB”) by a hotplate at 95° C. for 5 minutes. Then, the post-exposure bakedphotosensitive resin composition layer was immersed and developed in anSU-8 Developer (trade name, commercially available from MicroChem Corp.,propylene glycol monomethyl ether acetate as a major component) at 23°C. for 3 minutes, and rinsed with 2-propanol and dried, by which a curedresin pattern on the silicon wafer was obtained. The exposure dose atwhich the mask transfer accuracy became best was defined as an optimumexposure dose, and the resolving size at this time was taken as aresolution, and the sensitivity and the resolution were evaluated. Theresults are shown in the following Table 1.

(Evaluation of the Internal Stress Value of the Cured Product of thePhotosensitive Resin Composition)

The warping amounts of the substrate before and after the film formationof the silicon wafer (crystal orientation: 100, diameter: 100 mm,thickness: 0.5 mm) supported at three points were measured by using astylus-type surface shape measuring device, and a value obtained byconverting a change in the warping amounts before and after the filmformation was taken as the internal stress. Generally since the stressof a film is not affected by the shape and material of a substrate onwhich the film is formed, a value obtained by forming a film on asilicon wafer and measuring warping amounts of the substrate before andafter the film formation indicates an internal stress. In the case wherea resin film shrinks by curing, the internal stress becomes acompression stress; and depending on the magnitude of the stress, thestress of the cured film increases the warping of the substrate, andeven in the film itself, crazings and cracks are generated. A lowerinternal stress can reduce the warping of the substrate and eliminatethe generation of cracks in the film itself.

Each liquid resist obtained in Examples 1 to 10 and Comparative Examples1 to 4 was applied onto a silicon wafer by a spin coater, and pre-bakedby a hot plate at 95° C. for 10 minutes thereby obtaining aphotosensitive resin composition layer of 20 μm in dry film thicknessafter the application. Thereafter, the film surface on the wafer wasentirely irradiated with the optimum exposure dose for the correspondingcomposition acquired in the above evaluation through a photomask whichcould conceal only the edge bead part of the peripheral part of thesubstrate. Then, the film was subjected to PEB on a hot plate at 95° C.for 5 minutes, immersed and developed in an SU-8 Developer at 23° C. for3 minutes, rinsed with 2-propanol, dried and pre-hard baked on a hotplate at 120° C. for 30 minutes, thereafter hard baked in a convectionoven at 200° C. for 60 minutes, and allowed to fully cool. The warpingamount of each silicon wafer before the film formation and the warpingamount thereof after the film formation of the resist of thecorresponding composition were measured in a plurality of directions atthe same position by a surface shape measuring apparatus, and theinternal stress value was determined. The case where the internal stressvalue was lower than 10 MPa was represented as “◯”; the case where beinghigher than 25 MPa, “x”; and the results are shown in Table 1.

(Evaluation of Tight Adhesion after Treatment with Moisture and Heat)

A silicon wafer having a Pt metal of 200 nm vapor-deposited thereon, anLT substrate, and a silicon wafer having Ta of 100 nm vapor-depositedthereon were prepared; each of the liquid resists obtained in Examples 1to 10 and Comparative Examples 1 to 4 was applied onto each of thesesubstrates as described above. The substrate having the liquid resistapplied thereto was irradiated with the optimum exposure dose for thecorresponding composition obtained in the above sensitivity evaluationtest through a photomask provided with a test pattern for evaluation oftight adhesiveness. The process of hard baking after PEB was conductedin the same manner as in the process of the above stress evaluationtest, by which a cured resin pattern was prepared on the silicon wafer.The wafers with the resin pattern were individually immersed andsubjected to a test for moisture and heat in a PTFE closed vessel(relative humidity: 100%) filled with pure water at 85° C. for 24 hours.The adhesive force values of the resin pattern before and after the testwere measured by a shear strength tester; and the case where nodegradation in the adhesive force was observed was represented as “◯”,and the case where some degradation was observed was represented as “x”,and the results are shown in Table 1.

TABLE 1 Compositions for Evaluation and Results of Evaluation ofPhotosensitive Resin Compositions Examples Comparative Examples 1 2 3 45 6 7 8 9 10 1 2 3 4 Epoxy resin (A) (A-1) 60.0 60.0 60.0 75.0 48.0 60.060.0 17.0 50.0 65.0 10.0 (A-2) 5.0 (A-3) 10.0 10.0 10.0 12.5 8.0 10.010.0 3.0 10.0 (A-5) 20.0 20.0 20.0 19.0 20.0 20.0 20.0 8.0 20.0 (A-6)45.0 7.0 5.0 20.0 50.0 (A-7) 80.0 30.0 (A-8) 30.0 50.0 (A-9) 70.0 (A-10)50.0 Compound having phenolic (B-1) 10.0 10.0 10.0 12.5 25.0 hydroxylgroups (B) (B-2) 10.0 15.0 20.0 20.0 (B-3) 10.0 10.0 (B-4) 5.0 Cationic(C-1) 1.0 1.0 1.0 1.0 1.0 1.0 1.0 photopolymerization (C-2) 1.0 1.0 1.0initiator (C) (C-3) 4.0 4.0 4.0 4.0 Epoxy group-containing (D) 5.0 2.05.0 5.0 5.0 5.0 5.0 5.0 5.0 2.5 2.0 2.0 5.0 5.0 silane compound (D)Optimum exposure dose [mJ/cm²] 450 450 450 450 450 450 450 300 400 400350 550 200 500 Resolution [μm] 6 6 6 15 8 8 8 8 8 8 9 7 60 25 Weightedaverage WPE [g/eq.] 453 453 453 951 422 453 453 306 582 441 218 288 164161 Tight adhesiveness with moisture and heat *1 on Pt ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯◯ X X X X on LT ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ X X X X on Ta ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ XX X X Internal stress value [MPa] *2 ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ X X X X *1:Before and after 85° C. × 100% RH × 24 hours treatment; ◯: Nodegradation in adhesive force was observed; X: Some degradation inadhesive force was observed. *2: Residual stress of cured product: ◯:<10; and X: 25<

Compounds (A-1) to (D) listed in Table 1 are as follows, respectively.Further, the weighted average epoxy equivalent values were determinedfrom parts by mass indicated in Table 1, epoxy equivalents describedbelow, and blend ratios of components. The weighted average epoxyequivalent values are shown in one column in Table 1.

<Component (A): Epoxy Resins>

(A-1) jER4004P (trade name, commercially available from MitsubishiChemical Corp., an epoxy resin having an average repeating number in theformula (1): m≈5.6, epoxy equivalent: 868 g/eq.)

(A-2) jER4005P (trade name, commercially available from MitsubishiChemical Corp., an epoxy resin having an average repeating number in theformula (1): m≈7.0, epoxy equivalent: 1,046 g/eq.)

(A-3) jER4007P (trade name, commercially available from MitsubishiChemical Corp., an epoxy resin having an average repeating number in theformula (1): m≈16.1, epoxy equivalent: 2,218 g/eq.)

(A-5) YDF-8170C (trade name, commercially available from Nippon Steel &Sumikin Chemical Co., Ltd., epoxy equivalent: 160 g/eq.)

(A-6) NER7604 (trade name, commercially available from Nippon KayakuCo., Ltd., an epoxy resin represented by the formula (3), epoxyequivalent: 345 g/eq.)

(A-7) EPON SU-8 (trade name, commercially available from MomentivePerformance Materials Inc., epoxy equivalent: 200 g/eq.)

(A-8) Celloxide 2021P (trade name, commercially available from DaicelCorp., epoxy equivalent: 126 g/eq.)

(A-9) EP828 (trade name, commercially available from Mitsubishi ChemicalCorp., epoxy equivalent: 189 g/eq.)

(A-10) XD-1000 (trade name, commercially available from Nippon KayakuCo., Ltd., epoxy equivalent: 248 g/eq.)

<Component (B): Compounds Having Phenolic Hydroxyl Groups>

(B-1) PN-152 (trade name, commercially available from Meiwa PlasticIndustries Ltd., a phenol compound represented by the formula (2),hydroxyl equivalent: 105 g/eq.)

(B-2) H-1 (trade name, commercially available from Meiwa PlasticIndustries Ltd., a phenol compound represented by the formula (2),hydroxyl equivalent: 104 g/eq.)

(B-3) KAYAHARD GPH-65 (trade name, commercially available from NipponKayaku Co., Ltd., a phenol compound represented by the formula (5),hydroxyl equivalent: 200 g/eq.)

(B-4) XL-225-3L (trade name, commercially available from MitsuiChemicals Inc., a phenol compound represented by the formula (6),hydroxyl equivalent: 172 g/eq.)

<Component (C): Cationic Photopolymerization Initiators>

(C-1) Irgacure PAG290 (trade name, commercially available from BASF)

(C-2) GSID-26-1 (trade name, commercially available from BASF)

(C-3) CPI-210S (trade name, commercially available from San-Apro Ltd.)

<Component (D): Epoxy Group-Containing Silane Compound>

(D) 3-glycidoxypropyltrimethoxysilane

As seen in the results in Table 1, it was found that properties of thecompositions obtained in the Examples were as follows: the optimumexposure dose was small, and the sensitivity was high; the resolvingsize of sensitized patterns exhibited high resolution; the internalstress was low, and no cracks were generated in patterns; and the tightadhesiveness after the test for moisture and heat was kept.

Example 11 A Resist Laminate of the Photosensitive Resin CompositionAccording to the Present Invention

Further, ethylene glycol dimethyl ether was additionally blended to thecompositional ratios of Example 1 in Table 1, and stirred and dissolvedin a flask with a stirrer at 50° C. for 1 hour, and the mixture wasdiluted so that the solution viscosity at 25° C. became 2 Pa·s, allowedto cool, and thereafter subjected to a filtration using a membrane of1.0 μm in pore diameter, by which a lacquer for dry film resist of aphotosensitive resin composition according to the present invention wasobtained. The lacquer was applied uniformly onto a base film (made of apropylene, commercially available from Mitsubishi Plastics, Inc., filmthickness: 38 μm), and dried by a hot air convection drier at 65° C. for5 minutes and then at 80° C. for 15 minutes. Thereafter, a cover film(made of a polypropylene, commercially available from MitsubishiPlastics, Inc., film thickness: 38 μm) was laminated on the exposedsurface thereby obtaining a resist laminate (i.e. a photosensitive resincomposition laminate) in which the dry film resist having a thickness of20 μm was interposed by the based film and the cover film.

(Patterning of the Dry Film Resist)

The cover film was peeled off from the photosensitive resin compositionlaminate obtained in the above; the resultant was laminated on a siliconwafer at a roll temperature of 70° C. at an air pressure of 0.2 MPa, andat a rate of 0.5 m/min; and thereafter, the base film was peeled offtherefrom, by which a photosensitive resin composition layer (dry filmresist) of 20 μm was obtained. The photosensitive resin compositionlayer was contact-exposed by using an i line exposure apparatus (maskaligner, commercially available from Ushio Inc.). Thereafter, theresultant was subjected to PEB by a hot plate at 95° C. for 5 minutes,and immersed and developed in an SU-8 Developer (trade name,commercially available from MicroChem Corp., propylene glycol monomethylether acetate as a major component) at 23° C. for 3 minutes, and rinsedwith 2-propanol and dried, by which a cured resin pattern was obtainedon the substrate. There was obtained at an optimum exposure dose of 450J/cm² a cured product having no smears and no cracks, and havingvertical side walls of 6 μm in thin-line adhesion pattern width. It wasalso confirmed that the tight adhesiveness with moisture and heat oneach surface of Pt, LT, Ta had no degradation and was good. It wasconfirmed that the evaluation results of the internal stress were lowerthan 10 MPa, which were satisfactorily low.

INDUSTRIAL APPLICABILITY

The photosensitive resin composition according to the present inventionallows patterns having a fine and vertical side wall shape to be formedby photolithography method. Its cured product has properties excellentin the resistance to moisture and heat and the high tight adhesiveness.There can be provided the permanent resist and the cured productprovided with properties required by semiconductors and MEMS andmicromachine application fields, particularly package components forMEMS devices, semiconductor devices and frequency filter devices,components for forming microreactors, and inkjet printing headcomponents.

The invention claimed is:
 1. A photosensitive resin composition comprising: an epoxy resin (A); a compound having phenolic hydroxyl groups (B); and a cationic photopolymerization initiator (C), wherein the epoxy resin (A) has a weighted average epoxy equivalent of 300 g/eq. or higher; and the epoxy resin (A) comprises 20% by mass or more of an epoxy resin represented by the following formula (1):

wherein m is an average value and denotes a real number in the range of 3 to 35, and having an epoxy equivalent of 500 to 4,500 g/eq.; and the compound having phenolic hydroxyl groups (B) comprises at least one or more phenol compounds selected from the group consisting of phenol compounds represented by the following formulae (2), (4), (5) and (6):

wherein n is an average value and denotes a real number in the range of 1 to 10; and each R independently denotes a hydrogen atom or an alkyl group having 1 to 4 carbon atoms,

wherein q is an average value and denotes a real number in the range of 1 to 10,

wherein z is an average value and denotes a real number in the range of 1 to 10, and

wherein y is an average value and denotes a real number in the range of 1 to 10; and R₈ and R₉ each independently denote a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
 2. The photosensitive resin composition according to claim 1, wherein the epoxy resin (A) comprises an epoxy resin represented by the following formula (3):

wherein a is an average value and denotes a real number in the range of 2 to 30; and each X independently denotes a hydrogen atom or a glycidyl group and at least one of the plurality of X is a glycidyl group.
 3. The photosensitive resin composition according to claim 2, comprising 0.1 to 0.9 equivalents of the compound having phenolic hydroxyl groups (B) with respect to 1 equivalent of the epoxy resin (A).
 4. The photosensitive resin composition according to claim 2, wherein the cationic photopolymerization initiator (C) is a cationic photopolymerization initiator of an onium complex salt.
 5. The photosensitive resin composition according to claim 2, comprising an epoxy group-containing silane compound (D).
 6. The photosensitive resin composition according to claim 2, comprising a solvent (E).
 7. A cured product of the photosensitive resin composition according to claim
 2. 8. A resist laminate, obtained by interposing the photosensitive resin composition according to claim 2 between substrates.
 9. A cured product of a dry film resist obtained from the resist laminate according to claim
 8. 10. The photosensitive resin composition according to claim 1, comprising 0.1 to 0.9 equivalents of the compound having phenolic hydroxyl groups (B) with respect to 1 equivalent of the epoxy resin (A).
 11. The photosensitive resin composition according to claim 1, wherein the cationic photopolymerization initiator (C) is a cationic photopolymerization initiator of an onium complex salt.
 12. The photosensitive resin composition according to claim 1, comprising an epoxy group-containing silane compound (D).
 13. The photosensitive resin composition according to claim 1, comprising a solvent (E).
 14. A cured product of the photosensitive resin composition according to claim
 1. 15. A resist laminate, obtained by interposing the photosensitive resin composition according to claim 1 between substrates.
 16. A cured product of a dry film resist obtained from the resist laminate according to claim
 8. 